Description

Dual-purpose gun used only on the I 65 (Type KD 5) class and I 68 (Type KD 6A) class submarines. On 5 May 1942 the I 65 class were redesignated as the I 165 class and the I 68 class redesignated as the I 168 class.

There were two versions of the gun barrel. Model Type I used a radially expanded, removable lining while the Model Type I2 was of monobloc construction. Both types used horizontally sliding breech blocks.

The propellant grain used for this gun was too large and unburnt propellant was present at the muzzle, meaning that the muzzle velocity was unpredictable.

Gun Characteristics

Designation 10 cm/50 (3.9") Type 88 (Model 1928)
Ship Class Used On I 65 / I 165 and I 68 / I 168 classes
Date Of Design 1928
Date In Service 1932
Gun Weight 6,239 lbs. (2,830 kg)
Gun Length oa 208.7 in (5.300 m)
Bore Length 196.9 in (5.000 m)
Rifling Length 169.1 in (4.295 m)
Grooves (32) 0.049 in deep x 0.219 in (1.25 mm x 5.565 mm)
Lands 0.167 in (4.252 mm)
Twist Uniform RH 1 in 28
Chamber Volume 488 in3 (8.0 dm3)
Rate Of Fire 6 rounds per minute 1
  • ^This weapon had a firing cycle of 5 seconds but the pneumatic hoist took 10 seconds to deliver a round.

Ammunition

Type Fixed
Complete Round Weight 52.9 lbs. (24 kg)
Projectile Types and Weights HE: 28.7 lbs. (13 kg)
Bursting Charge HE: 2.1 lbs. (1 kg)
Projectile Length 15.0 in (38.0 cm)
Propellant Charge 9.11 lbs. (4.13 kg) 30 DC
Cartridge: 24.2 lbs. (11 kg)
Muzzle Velocity 2,904 to 2,936 fps (885 to 895 mps)
Working Pressure 17.9 tons/in2 (2,820 kg/cm2)
Approximate Barrel Life 400 - 700 rounds
Ammunition stowage per gun N/A

Range

Range with 28.7 lbs. (13 kg) HE
Elevation Range
45 degrees 17,700 yards (16,200 m)
AA Ceiling @ 90 degrees 36,750 feet (11,200 m)

Mount/Turret Data

Designation Single Pedestal
   I 65 / I 165 (1): N/A
   I 168 (1): N/A
Weight N/A
Elevation -10 / +90 degrees
Elevation Rate Hand operated, only
Train about +150 / -150 degrees
Train Rate Hand operated, only
Gun recoil N/A

Sources

"Naval Weapons of World War Two" by John Campbell
"Japanese Warships of World War II" by A.J. Watts
"The Japanese Ships of the Pacific War" by The Koku-Fan

Page History

27 August 2007 - Benchmark
27 May 2012 - dated to latest template
16 February 2020 - Added I 168 class, re-scanned photograph, converted to HTML 5 format